This application claims priority under 35 U.S.C. xc2xa7119(b) to European application serial no. 02 006 822.7, filed on Mar. 25, 2002.
The present invention relates to an insulated pipe arrangement, comprising at least two pipe bodies, each of which has an inner fluid-guiding pipe which is enclosed by an insulating layer made of elastomeric or thermoplastic foam, a protective film made of a thermoplastic, elastomer, or duromer of high density being arranged around the insulating layer, as well as a method for producing such an insulated pipe arrangement.
Welding two pipe bodies to one another, each of which comprises an inner fluid-guiding pipe made of metal or plastic which is enclosed on the outside by an insulating plastic, which in turn has an outer casing made of polyethylene, along peripheral parts opposite one another in the axial direction through the effect of heat, is already known. If such a pipe arrangement formed by two pipes has to be connected to connections which are at a distance to one another that is greater than the spacing of the metal pipes of the welded pipe bodies, the weld seam is detached through the corresponding effect of force on the two pipe bodies. In the event of such tearing of the weld seam, the polyethylene film forming the outer layer is damaged, so that it no longer offers a protective effect at the peripheral parts of the previous weld. When the weld seam is opened too far and therefore must be closed again, this requires renewed welding or gluing, which is very costly.
A conduit system for piping facility components in the field of heating technology, in which two flexible metal pipes are embedded at a distance to one another in a shared foam body having an oval or elliptical cross-section, which is enclosed on the outside by a protective film, is known from German Utility Model 299 23 057 U1. An intended breaking point is provided between the two flexible metal pipes in the insulating body, which allows breaking apart in the axial direction so that the two pipes may be connected to connections whose distance is greater than that of the pipes in the insulating body, which forms one piece. Reconnection of the individual pipe bodies separated along the intended breakpoint is only possible by applying adhesive.
The object upon which the present invention is based is to design the pipe arrangement of the type initially cited in such a way that the at least two pipe bodies may be separated from one another and reconnected to one another at the same point without problems.
This object is achieved, on the basis of the insulated pipe arrangement of the type initially cited, in that the pipe bodies are connected to one another on opposing peripheral parts of their protective film by a layer of adhesive which allows detachment of the adhesive bond without the protective film being damaged, and which produces a renewed adhesive bond after detachment of the adhesive bond when the peripheral parts of the previous adhesive bond are brought into contact again.
Such an adhesive is expediently a pressure-sensitive adhesive, preferably based on acrylic, or an adhesive in the form of a synthetic thermoplastic rubber. The protective film is expediently made of polyethylene, polyvinyl chloride, rubber, or other thermoplastics. The pipe bodies may have the same diameter or different diameters.
The adhesive bond of the two pipe bodies remains in existence even if the insulated pipe arrangement is wound onto a drum or laid in an annular shape, for example.
The insulated pipe arrangement according to the present invention allows separation of the two pipe bodies from one another at one end of the pipe arrangement by pulling the pipe bodies away from one another. The bond is detached in the region of the layer of adhesive, without the protective film at the peripheral parts of the adhesive bond being damaged in this way. The composition of the adhesive allows reproduction of the adhesive bond merely by pressing the peripheral parts, which have the layer of adhesive forming the previous adhesive bond, against one another.
Such an insulated pipe arrangement is produced according to a method in which an insulating layer made of an elastomeric or thermoplastic foam, in which an opening is or will be formed in the axial direction, is laid around each of at least two continuously transported flexible and/or easily bendable inner pipes for fluid guiding. The axial opening is closed into an insulating hose by interposing a hot-melt adhesive. A protective film made of a thermoplastic, elastomer, or duromer of high density, in the range of 200 to 2000 kg/m3, for example, is extruded onto the insulating hose to form a pipe body. Subsequently, the pipe bodies are moved toward one another, with a layer of an adhesive being interposed between opposing peripheral parts, and bonded to one another using adhesive along the peripheral parts of the protective parts. The adhesive bond is detached, without damaging the protective film, by pulling the pipe bodies away from one another, and is reproduced by pressing the peripheral parts which formed the previous adhesive bond against one another again.
Thin metal pipes, such as copper pipes, pipes made of plastic, or composite pipes, for example those made of aluminum and plastic, are used as the inner flexible or easily bendable pipes. The foam may be produced in the form of a slab which is laid around the metal pipe and bonded along the axial opening, or by a hose which is cut before being laid around the metal pipe and is bonded back into one piece by gluing the cut surfaces after being laid around the metal pipe.